The present invention relates to a breather system for a crankcase of an internal combustion engine of the type which recirculates piston blow-by gases in the crankcase to the intake air line of an engine to eliminate the discharge of oil mist into the environment.
Ideally, the pressure within an internal combustion engine crankcase should be maintained at a level equal to or slightly less than atmospheric pressure to prevent external oil leakage through the various gasketed joints, such as that between the valve cover and the cylinder head. Combustion gases are generated during the operation of an internal combustion engine. A small amount of these gases leaks past the piston seals of the internal combustion engine, and unless the gases are removed from the crankcase, they become trapped. These gases, commonly referred to in the art as “blow-by” gases, need to be released. Because of the “blow-by” gases, the crankcase pressure will inherently rise, promoting leakage of oil from the crankcase. Originally, crankcase pressure was vented to the atmosphere through a breather to solve this problem.
Environmental considerations dictate that the blow-by gases in the crankcase be vented back to the combustion chamber rather than being released to the atmosphere. Accordingly, the crankcase was scavenged by being connected to the engine air intake thereby resulting in a vacuum in the crankcase with a depression valve being used to prevent the negative pressure in the engine cavity from exceeding a predetermined amount.
Some efficient engine breather systems incorporate a centrifuge. These systems require a drive which is typically a high-speed motor or an oil jet directed at a wheel. Durability and service life are important considerations for these devices as they are operated at rotating speeds above 10,000 rpm. Furthermore, these devices require dedicated space within an engine compartment for mounting and supporting hardware.
The present inventors have recognized that it would be desirable to provide a durable breather system that did not require significant additional space within an engine compartment.